Aerodynamic bearing for axial and / or radial support of a shaft and method for producing such a bearing

Abstract

The invention relates to an aerodynamic bearing (1) for the axial and / or radial support of a shaft (2) for a turbocompressor extending along a rotational axis (A), wherein the aerodynamic bearing (1) comprises a first bearing part (10) which can be designated as a rotor and a second bearing part (20) which can be designated as a stator, relative to which the first bearing part (10) is rotatable about the rotational axis (A), wherein the first bearing part (10) and / or the second bearing part (20) has a bearing surface (11, 21) facing the respective other bearing part (10, 20), on which an air cushion (3) for aerodynamic support can be generated between the bearing parts (10, 20), wherein the bearing surface (11, 21) has a plurality of recesses (12), each of which follows a predetermined longitudinal profile (13) on the bearing surface (11, 21) and is arranged in a predetermined pattern, wherein the recesses (12) are provided along their respective longitudinal extent (13) on the bearing surface (11,21) each have a varying depth (T) which is determined by a depth profile (30) limited to a predetermined number of depth levels (31, 32, 33, 34),

Description

[0001] The invention relates to an aerodynamic bearing for the axial and / or radial support of a shaft extending along a rotational axis and to a method for producing such a bearing.

[0002] Aerodynamic bearings, which can also be referred to as gas or air bearings, have long been known in the state of the art. They create a gas or air cushion between two bearing components or the bearing surfaces provided by them, acting as a lubricant, allowing the bearing components or bearing parts to rotate relative to each other essentially without contact or friction.

[0003] In order to increase stability or the maximum possible speeds with the bearing, it has long been known to create recesses in the bearing surfaces through which the air cushion remains uniform and resilient, especially at high speeds, so that even at high speeds or when the bearing is subjected to high loads on the bearing surfaces, the pressure distribution required for the bearing is maintained.

[0004] The recesses can be spiral-shaped in axial bearings, for example, and arrow-shaped in radial bearings, for example, and can each be arranged in a herringbone pattern so that adjacent recesses engage with each other without contact.

[0005] Tests and calculations have shown that it is further advantageous if the depressions have a varying depth along their respective course, although it has been shown that a continuous or jump-free depth profile can only be produced with great effort using common manufacturing methods, such as lasers.

[0006] The invention is therefore based on the object of overcoming the aforementioned disadvantages and providing an aerodynamic bearing that is easy to manufacture and with which high speeds can be achieved.

[0007] This problem is solved by the combination of features according to patent claim 1.

[0008] According to the invention, an aerodynamic bearing is therefore proposed for the axial and / or radial mounting of a shaft extending along a rotational axis for a turbocompressor, which shaft is preferably a high-speed turbocompressor. The turbocompressor can be designed as a radial, axial or diagonal compressor. Although the features explained below can also relate to an axial bearing, they preferably relate to a radial bearing. Accordingly, the aerodynamic bearing has a first bearing part (rotatable with the shaft or formed integrally by the shaft), which can be referred to as a rotor, and a second bearing part, which can be referred to as a stator, relative to which the first bearing part is rotatable about the rotational axis. In the case of an axial bearing, the bearing parts are preferably designed as adjacent bearing rings, one of which is sleeve-shaped oris fixed to the shaft like a flange. In a radial bearing, one of the bearing parts extends in the circumferential direction around the shaft and is preferably formed integrally by the shaft, wherein the other bearing part rotates around the shaft and is hollow cylindrical. Irrespective of whether it is designed as an axial or radial bearing, it is therefore provided in each case that the first bearing part and / or the second bearing part has a bearing surface facing the other bearing part, on which bearing surface an air cushion or gas cushion for aerodynamic support can be generated between the bearing parts, which due to its small thickness can also be referred to as an air or gas film, for example. To make it easier to distinguish, the bearing surfaces can also be referred to as rotor bearing surface and stator bearing surface. Furthermore, the bearing surface orBoth bearing surfaces have a plurality of depressions, each of which follows a predetermined longitudinal profile on the bearing surface and is arranged in a predetermined pattern. Due to their predetermined longitudinal profile, the depressions can also be referred to, for example, as a channel or groove. According to the invention, the depressions each have a depth that varies relative to the bearing surface along their respective longitudinal profile on the bearing surface, which depth is determined by a depth profile that is limited to a predetermined and finite or finite number of, in particular, discrete depth levels.

[0009] The proposed depth profile can therefore be described as a discrete depth profile in contrast to a depth profile with infinitely many (infinite) depth levels that can be described as a continuous depth profile.

[0010] By limiting the depth profile to a predetermined number of predetermined depth levels, manufacturing is significantly simplified so that such a bearing can be easily manufactured and supplied.

[0011] The depth profile can be in three to twelve, in particular four to ten depth levels, or the number of depth levels can be limited to three to twelve or four to ten.

[0012] The respective transition between the depth levels is comparatively flat and accordingly at an angle of less than 34°, more preferably the angle is between 2° and 20°.

[0013] The transition between the depth levels preferably has a length between 10 and 100 µm, in particular between 40 and 60 µm and more particularly 50 µm, wherein the individual depth levels or their course between two transitions preferably have a length between 1 and 20 µm, more preferably between 2 and 10 µm.

[0014] As explained in the context of the proposed manufacturing methods, the depth profile according to the invention can be a native discrete depth profile or a discrete depth profile as an approximation to a continuous depth profile.

[0015] Immediately adjacent depth levels can have a distance of between 1 and 20 µm, in particular 2 and 10 µm, from each other in terms of their depth, whereby the distances between the different depth levels can be different, so that the gradation achieved by the depth levels can be irregular.

[0016] In order to be able to generate an optimal pressure distribution, particularly in the case of asymmetric load distribution, it can also be provided that the depth profile is symmetrical or asymmetrical with respect to a center point of the longitudinal profile formed, for example, by a vertex.

[0017] Although the depth profiles of the depressions can fundamentally be different, it is preferably provided that the depth profiles of all depressions are the same.

[0018] Furthermore, it should be noted that the respective longitudinal course or courses of the depressions consist exclusively of straight sections or can at least be curved in sections.

[0019] The longitudinal course can form an arrow shape so that the recesses each have two sections connected by a kink.

[0020] Furthermore, the depressions can have a constant or varying width along their respective longitudinal course on the bearing surface, whereby it should be added that a continuous, i.e. jump-free or step-free, variation of the width is usually possible without problems using modern manufacturing methods and, for example, lasers, unlike a variation of the depth.

[0021] As already mentioned, the recesses are preferably arranged in a herringbone pattern, which preferably means that the recesses overlap at least partially in a predetermined direction of rotation and, in the case of a radial bearing, in the circumferential direction around the axis of rotation and thus engage with one another without contact.

[0022] A further aspect of the invention relates to a method for manufacturing an aerodynamic bearing proposed according to the invention. By simulation and / or calculation, for example using numerical calculation methods or the finite difference method, a continuous depth profile is first determined for optimal pressure distribution on the bearing surface at a maximum rotational speed. Subsequently, this continuous profile, which is usually impossible or difficult to achieve, is approximated by interpolation or approximation with the depth profile limited to the predetermined number of depth levels.

[0023] As an alternative to this determination of the discrete depth profile via the continuous depth profile, the discrete depth profile can also be determined natively, i.e. by taking into account during the simulation and / or calculation, for example using numerical calculation methods or the finite difference method, that the depth profile is limited to the predetermined number of depth levels, so that the depth profile limited to the predetermined number of depth levels is determined natively, i.e. directly, for an optimal pressure distribution on the bearing surface at a maximum rotational speed.

[0024] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0025] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below, together with the description of the preferred embodiment of the invention, with reference to the figures. They show: Fig. 1 an aerodynamic bearing designed as a radial bearing; Fig. 2 a depth profile of the recesses of the bearing according to Figure 1 .

[0026] The figures are schematic examples. Identical reference numerals in the figures indicate identical functional and / or structural features.

[0027] In Figure 1 an aerodynamic bearing 1 for the radial support of a shaft 2 extending along the rotation axis A is shown, which can also be referred to as a radial bearing 1 and is intended in particular for use in a high-speed turbocompressor.

[0028] Accordingly, the bearing 1 has two bearing partners or two bearing parts 10, 20. The first bearing part 10 is designed as a rotor integral with the shaft 2 and is rotatable about the rotation axis A. The second bearing part 20 is designed as a stator and surrounds the first bearing part 10 in the circumferential direction U completely and in a ring shape, so that the Figure 1 The second bearing part 20 shown in section essentially corresponds to a hollow cylinder.

[0029] The bearing parts 10, 20 each have a bearing surface 11, 21 which face each other, so that when the first bearing part 10 rotates, an air or gas cushion 3 is formed between the bearing surfaces 11, 21, which serves as a lubricant or sliding agent for the bearing.

[0030] In order to achieve an optimized pressure distribution of the lubricating medium, i.e., the gas or air, on the bearing surface 11 of the first bearing part 10 or on the rotor bearing surface 11 of the rotor 10, even at high speeds, a plurality of recesses 12 are provided on the first bearing surface 11, each extending in an arrow-shaped manner along a longitudinal profile 13. Accordingly, the identical longitudinal profiles 13 of the recesses 12 each have two straight sections, which are connected to one another by a kink or apex.

[0031] As in Figure 1 As can be clearly seen, the arrow-shaped depressions 12 overlap in the circumferential direction U, resulting in a pattern similar to a herringbone pattern.

[0032] Although the depressions 12 are shown here with a constant width B - with the exception of the edge or bend areas - the width B can also vary over the longitudinal extent 13.

[0033] In addition to the width B and the longitudinal profile 13, the pressure distribution on the bearing surface 11 is also influenced in particular by the depth T of the recess 12, it being shown that the pressure distribution of the air or gas in the pressure cushion 3 can be optimized in particular and correspondingly higher speeds can be achieved if the depth T of the recess 12 does not remain constant over its longitudinal profile 13, but is varied.

[0034] By simulation and / or calculation, a depth profile can be determined for the variation of the depth T, by which the depth T of the recess 12 along the longitudinal profile 13 is determined for the desired optimized pressure distribution on the first bearing surface 11.

[0035] However, if this depth profile is determined as a continuously changing profile, ie a profile that can be described as a continuous depth profile 40, it is difficult or impossible to produce.

[0036] Therefore, according to the invention, the variation of the depth is limited to specific depth levels 31, 32, 33, 34, so that the depth T can essentially only assume the values determined by the depth levels 31, 32, 33, 34. This results in a depth profile 30 limited to a predetermined number of depth levels 31, 32, 33, 34, which can also be referred to as a discrete depth profile 30.

[0037] In Figure 2 Both a continuous depth profile 40 and a discrete depth profile 30 are plotted over a longitudinal profile 13 of a depression 12, wherein the position X along the longitudinal profile 13 is specified without a size, so that 0 corresponds to a starting point of the longitudinal profile 13 and 1 to an end or vertex point of the longitudinal profile 13.

[0038] In principle, the depth profile 30 limited to the predetermined number of depth levels 31, 32, 33, 34 can be determined starting from a previously determined continuous depth profile 40, so that the discrete depth profile 30 corresponds to an approximation of the continuous depth profile 40.

[0039] Alternatively, during the calculation or simulation for determining the optimal course of the depth T, it can be taken into account that the depth T can only assume or have the predetermined depth levels 31, 32, 33, 34, so that the discrete depth course 30 occurs directly or natively and without the prior determination of a continuous depth course 40.

[0040] This shows Figure 2 also an asymmetry of the depth profile 30, by means of which, for example, a likewise asymmetric load distribution on the bearing 1 can be taken into account.

[0041] Irrespective of this, it must be taken into account that due to the manufacturing processes that can be used, there is a steep transition 35 between the individual depth levels 31, 32, 33, 34, which is usually not orthogonal to the depth levels 31, 32, 33, 34 and has an angle between 45° and 90°.

[0042] The invention is not limited to the preferred embodiments described above. Rather, a number of variants are conceivable that utilize the solution presented even in fundamentally different embodiments.

Claims

1. Aerodynamic bearing (1) for the axial and / or radial support of a shaft (2) for a turbocompressor, said shaft extending along a rotational axis (A), wherein the aerodynamic bearing (1) comprises a first bearing part (10) which can be designated as a rotor, and a second bearing part (20) which can be designated as a stator, relative to which the first bearing part (10) is rotatable about the rotational axis (A), wherein the first bearing part (10) and / or the second bearing part (20) comprises a bearing surface (11, 21) facing the respective other bearing part (10, 20), on which an air cushion (3) for aerodynamic support can be generated between the bearing parts (10, 20), wherein the bearing surface (11, 21) comprises a plurality of depressions (12), each of which follows a predetermined longitudinal profile (13) on the bearing surface (11, 21) and is arranged in a predetermined pattern, wherein the Recesses (12) along their respective longitudinal extent (13) on the bearing surface (11,21) each have a varying depth (T) which is determined by a depth profile (30) limited to a predetermined number of, in particular, discrete depth levels (31, 32, 33, 34).

2. Aerodynamic bearing according to claim 1, wherein the depth profile (30) extends in three to twelve depth levels (31, 32, 33, 34).

3. Aerodynamic bearing according to claim 1 or 2, wherein a respective transition (35) between the depth levels (31, 32, 33, 34) occurs at an angle of less than 45° and in particular at an angle between 2° and 20°.

4. Aerodynamic bearing according to one of the preceding claims, wherein immediately adjacent depth levels (31, 32, 33, 34) have a distance between 1 and 20 µm, in particular 2 and 10 µm, from one another.

5. Aerodynamic bearing according to one of the preceding claims, wherein the depth profile (30) is symmetrical or asymmetrical with respect to a center point of the longitudinal profile (13).

6. Aerodynamic bearing according to one of the preceding claims, wherein the longitudinal profile (13) consists exclusively of rectilinear sections or is at least curved in sections and / or wherein the longitudinal profile (13) each forms an arrow shape, so that the depressions (12) each have two sections connected by a kink.

7. Aerodynamic bearing according to one of the preceding claims, wherein the recesses (12) each have a constant or varying width (B) over their respective longitudinal extent (13) on the bearing surface (11, 21).

8. Aerodynamic bearing according to one of the preceding claims, wherein the recesses (12) are arranged in a herringbone pattern and / or overlap at least partially in a predetermined direction of rotation about the axis of rotation (A).

9. Method for producing an aerodynamic bearing according to one of the preceding claims, wherein a continuous depth profile (40) for an optimal pressure distribution on the bearing surface (11, 21) at a maximum rotational speed is determined by simulation and / or calculation and wherein the depth profile (30) limited to the predetermined number of depth levels (31, 32, 33, 34) is determined by interpolation or approximation, which approximates the continuous depth profile (40).

10. A method for producing an aerodynamic bearing according to one of the preceding claims 1 to 8, wherein the depth profile (30) limited to the predetermined number of depth levels (31, 32, 33, 34) is determined by simulation and / or calculation for an optimal pressure distribution on the bearing surface (11, 21) at a maximum rotational speed.

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